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)GRAPHIC MAPS OF THE UNITED STATES 



All wniev features are printed in blue, the smaller streams 
1111(1 ciiiKils in full blue lines akd the larger streams, lakes, 
and the sea in blue water-lining, j Intermittent streams — those 
whose beds are dry at least three months in the year — are 
shown by lines of dots and dashes. 

Relief is shown by contour hjies in broivn. A contour on 
the ground passas through poinds that have the same altitude. 
One who foliows^a-comour -will o}f^ fw4tiier^Ti|'*hiM'^TroT^downhil^ 
but on a level. The contour I v rhe map sliow not only 

the sluipes of the hills, mount, 1 valleys 1:)ut also their 

elevations. The line of the su:,, I'sfli* i>; a contour line, 

the datum or zero of elevation (fiieing -ea level. The 

contour at, say, 20 feet above s- would be the shore line 

if the sea were to rise or the lam _io iink 20 feet. On a gentle 
slope this contour is far from 
slope it is near the coast. W 
are far apart on the map they 
ihev nre close toirether thev ind 



p pi'esent coast; on a steep 

re su<'cessive contour lines 

gentle slope ; where 

air ;i >n.'t^p slopc; and where 



they ruu together in one line th. v indicate a cliff. 



The manner in which cont(i^ 
;ind grade is shown in the figure 



ex 



press altitude, form, 




(below. 




The sketch represents a river^^alley between two hills. In 
the foreground is tlie sea., with a bay that is partly inclosed 
by a hooked sand bar.^ On eacli side of the valley is a terrace 
into which small streams h&ve cut narrow gullies. The hill on 

till.' ri'j.iit h;!^ a roiin<led summit'and gently sloping spurs sepn- 

3 triiucated at their lower ends 

) 



1 y n sea cliff. The hill on the left terminates abruptly at the 

valley in a steep ■ It slopes gradually back a>vay from 

the scarp and fori.. ,,.;,, uiclined table-land, which is traversed 
hy a few shallow gillies. On the map each of these features 
is indit'iited, directij beneiith its position in the sketch, by 
contour lines. 

The contour inttir\al, or the vertical distance in feet between 
~6a-g=eogtour ajjd th^trg^T^s-gtated-at-i-lie-brjttonz of^ t^chmrap. 
This interval differs according to the character of the area 
n\apped; in a flnt country it may be as small as 5 feet; in a 
mountainous region it may be 250 feet. Certain contour lines, 
every fourth or fifth one, are made heavier than tbe others 
and are accompanied by figures stating elevation above sea 
level. The heights of many points, such as road corners, sum- 
mits, surfaces of lakes, and bench marks, are also given on the 
map in figures, Avliieh express the elevations to the nearest 
foot only. More exact elevations of bench marks, as well as 
geodetic coordinates of triaugidation stations, are published in 
bulletins issued by the Geological Survey. A bulletin per- 
taining to .■ijiy Sf;ite may be had on application. 

The works of man are shown in blcic/c, in which color all 
lettering also is printed." Boundaries, such im those of a State, 
county, city, land 'grant, township, or reservation, are shown 
by continuous or broken lines of different kinds and weights. 
Public and through i-oads are shown by fine double lines; 
private and poor roads by dashed double lines; trails by dashed 
single lint:'S. 

Each quadrangle mapped for the topographic atlas is desig- 
nated by the name of a principal town or of some prominent 
natural feature within the quadrangle, and on the margins of 
the maps are printed the names of adjoining quadrangL.'S for 
which atlas sheets ha\'e been published or are in preparation. 
The sheets are sold at. 10 cents each in lots of less than BO 
copies or at 6 cents each in lots of 50 or more copies, whether 
of the same or of different sheets. 

The topographic map is the base on which the geology and 
the mineral resources of a quadrangle are represented, the maps 
showing these feataves being bound together, with a description 
of the quadrangle, to form a folio of the Geologic Atlas of the 
United States. Circulars showing by index jii^ip.s the pub- 
lished topographic atlas sheets and geologic folios covering 
any State or region will be sent free cm application. 

Applications for maps or folios sliould be accompanied by 
cash — the exact amount — or Irv post-office money order and 
should be addressed to — 

THE DffiECTOli 

United States (reoJoyieal Sxrveijj 

Washington, D. C. 



Jul 



uuirv 



1013. 



V 



THE TOP- 



5 Geological Survey is making a topographic 

States. This work has beeii in progress 
3re than 38 per cent of the area of the 
)utlying possessions, has now been mapped. 

are widely distributed, every State being 
n on the progress maps accompanying each 

Director, 

1 g pTtl3ttBllM'"1ir"BtrenS'T7f°StmTCTt5nt'^ 

iclies. The four-sided area of land repre- 
heet is bounded by parallels and meridians 
■drangle. The quadrangles mapped cover 
,^ of longitude, 30' of latitude l>y 30' of 
itude by 15' of longitude, or smallor areas, 
ia mapped depending on the scale used. 
employed. The smallest scale, that used 
vering 1*", is 1:250,000, or very nearly 4 
-that is, 4 linear miles on [lu; ground is 
near inch on tlie map. This scale is used 
ert regions and some other parts of the fiu- 
^ater part of tlie countrv, which is maj;»ped 
vering )\i)'.. ;i : l:125,00(i, or 

I inch, is eiuployecl. A slili larger scale, 
I mile to an inch, is used for quadrangles 
flit selected for mapping thickly settled or 
nt ai'(';is. Afourth sr;ilf, l:ol,()S(), or one- 
,, is ennployetl for maps that are to be used 

irrigation or drainage, and a few in;i]-)s of 

published on stiU laro-er scales. 

rvey of Alaska h;^ 

) per cent of its eiuirt; area iius now been 

1 of the area mapped, or 10 per cent of the 

covered only by re(M)nnaissanee work, the 
•-e been ma]>ped oii a scale of about 10 miles 
aps of nearly all the remaining two-thirds 
rea have been published on a scale of 
, 4 miles to an inch. These maps are largo, 
!° of latitude by 4"" of longitude. A few 

economic importance, aggregating about 
, have been surveyed in greater detail and 
)f 1 : 62,500, or about a mile to an inch. 
Hawaiian Islands was begun in 1910 and 
are being published on a scale of 1:62,500. 
wn on these atlas sheets or maps may In 
ips — (1) water, including seas, lake- 
I other bodies of Avater; (2) reUef, luciuu- 
S valk'vs, and other dcvnfions and depres- 
works of man), su. ,ns, cities^roads 



daries. TIk* conventional signs used 



lown belo\v, with explanations. 
icr maps. 



Yim